Electromagnetic pick-up device



Sept. 2, 1930, R. HILLNER 1,774,975

ELECTROMAGNETIC PICK-UP DEVICE Filed April 1, 1926 lnvhfior:

Rudolph Hillner,

H IS Attorney Patented Sept. 2, 1930' UNITED STATES.

BUDOLP H HILLNER, OI! SCHENECTQADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC PATENT OFFICE.

COMPANY, A CORPORATION OF NEW YORK I ELECTROMAGNETIC PICK-UP DEVICE Application filed April 1,

. or reproduced Various devices have been utilized in the past to reproduce sound, either directly or by the generation of electromagnetic impulses dependent on the character of the sound to be transmitted. S'omeof these devices involve theuse of an armature member that is moved to'and fro, between the poles of a magnet in accordance with the contour of a record, such for example as the groove of a phonographic record. I In the construction and operation of such devices, difliculty is fre-- quently' encountered in maintaining the armature member in a position which ensures proper variation in the electrical impulses of the coil when the armature is moved to and fro by rotation of the record. The principal object of my invention is to provide means whereby the armature of a sound producing device may be readily and accurately adjusted to a position that ensures the proper operation of the device.

My invention will be better understood from the following description when considered inconnection with the accompanying drawings and its scope will be pointed ,out in the appended claims.

Referring to the drawings, Fig. 1 is a plan View of a sound producing device wherein my invention has been embodied; Fig. 2 is a sectional. view taken on the line aa of Fig. 1; Fig. 3 shows certain details in the means for adjusting the armature to a preterminal block 7 which is clamped to the 1926. Serial n. 99,166.

upper surfaces of the pole pieces 2 and 3 by means of studs 8 and 9 extending through the terminal block and the pole pieces. An armature member 10 is arranged to be vibratcd between the upper projections of the pole pieces 2 and 3 for the purpose of varying the direction in which the flux 'of the magnet threads the coil 4. The armature member 10 is provided with asquare shaft 11 mounted in-a resilient bearing formed by resilient members 12 interposed between the shaft 11 and the ends of the lower projections of the pole pieces 1 and 2. It will'be observed that a needle 13 is clamped in the lower end of the armature 10 by means of a screw 14 threaded into the end of the shaft 11, and that pads 15 and 1.6 made of rubber or other resilient material, are provided at the upper end of. the armature member for damping its motion and producing a biasing force augmenting that exerted through the resilient journal members 12.

As shown more clearly in Figs. 2, 3 and 4, the studs 8 and 9 are surrounded by rotatable membersl? and 18 which are interposed between the insulation terminal block 7 and the pole-pieces 2 and 3 and are respectively provided with cam-shaped or eccentric portions 19 and 20 arranged to cooperate with members 21 and-22. The members 21 and 22 are provided with stop members or projections 23 and 24, which engage the resilient pads 15 and 16 as the armature 10 is moved to and fro between the ends of the pole pieces 2 and 3. i

In assembling the pole pieces 2 and 3 and the armature 10, difliculty is encountered due to the fact that the armature 10 is likely to be biased to a position where it is not properly spaced between the'pole pieces and does not accurately reproduce the impulses imparted to it by the needle 13. In the illustrated embodiment of the invention, this difii'culty is avoided by members 17 and 18 which may be rotated about the bolts 8 and 9 respectively to adjust the stop members 23 and 24 to positions where the armature 10 is maintained in a position such that the impulses imparted to it by the needle 13 are faithful-1y reproduced and the current impulses induced -'being modified to meet the different conditions encountered in its use' andI therefore in the coil 4 at all times correspondto the sound impulses that are to be produced "or reproduced.

The embodiment of trated and described herein has been selected for the purpose of clearly setting forth the principles involved. It will be apparent, however, that the invention is susceptibleof aim to cover by the appended claims all modifications within the true spirit and scopeof my invention. Y I

What I claim as new and desireto secure by Letters Patent of the, United States, is

,1. The combination of a magnet, a coil inte'rposed in the flux path of said magnet, an armaturearranged to be vibrated between the poles of said magnet for varying the path of the'flux' transmitted through said coil by said magnet, means for damping said armature, a cam-shaped member, and means for adjusting saidfarmature to a redetermined positionbetween the poles 0 said magnet,- said means including said damping means and means including said cam-shaped memher for adjusting said damping means.

2. The combination of a magnet, a coil terposed in the flux path of said ma net, an armature arranged-t0 be vibrated the poles of said magnet for varying the path of the flux transmitted through said coil by said magnet, means for damping sa'id armature, an eccentric rotatable member, and means for adjusting the bias of said armature to a predetermined position between the poles of said magnet, said means including said damping means and means including said eccentric rotatable member for adjusting said damping means.

3. The combination of a magnet, a coil interposed in the flux path of said magnet, an armature arranged to be vibrated between the poles of said magnet for varying the path of the flux transmitted through said coil by said magnet, means for damping said armature, an eccentric rotatable member, and meansfor adjusting the bias of said armature member to a predetermined position between the poles o said magnet, said means including said damping means and means controlled by said eccentric rotatable member for adjusting said damping means.

In witness whereof, I have hereunto set my hand this 31st day of March, 1926.

RUDOLPH HILLNER.

the invention illus'- etween 

